In this paper the characteristics of Sq variation of geomagnetic field in the region of the Chinese Great Wall Station (CGWS), Antarctica, in winter are analyzed from geomagnetic data obtained at the Geomagnetic Observatory of CGWS. The result enables us to reveal the following aspects: (1) The pattern of Sq variation at CGWS in early (Apr.) and Late winter (Sep.) is similar to that at Beijing Geomagnetic Observatory (BJO) at the middle latitude in the Northern Hemisphere. It may be controlled by the midlatitudinal ionospheric dynamo current. Amplitude of Sq variation is very small, and the harmonics in 8 hours or shorter periods in midwinter (June and July) is predominant because of the decreased effect of solar ultraviolet radiation and the dominant geomagnetic disturbance at high latitudes. (2) The vectors of Sq-equivalent current in the daytime are about five times more than that in (he night. The direction of the vectors is clockwise in the daytime (08—15h) and counterclockwise in the night in early and late winter. Both of the vectors are very small because of the effect of the current density in the ionosphere is relatively weak in midwinter. The direction of vectors of Sq-equivalent current at CGWS in early and late winter is different from that in midwinter. It may be affected by the ionospheric current and field-aligned current in the polar region.
RESEARCH-ARTICLE | Geology/Petrology
CHARACTERISTICS OF Sq VARIATION OF GEOMAGNE TIC FIELD AT THE GREAT WALL STATION, ANTARCTICA IN WINTER
1.Institute of Geophysics, Academia Sinica, Beijing 100101
1 Brown, G. M. and Williams, W. R. (1969): Some properties of the day-to-day variability of Sq(H); Planet. ., 17, 455-470.
Space Sci DOI:10.1016/0032-0633(69)90076-2
2 Mead (1973): Nagata, T. and Kokubun, S. (1969): An additional geomagnetic daily variation field (Sq-field) in the polar region on geomagneticaUy quiet day. Rep. Ionos. Space Res., Japan, 16, 256.
3 Parkinson, W. D. (1983): Introduction to geemagnetism, Scotish Academic Press, Edingburgh and London, 269.
4 Petrova, G. N., Bobrov et al. (1980): Geomagnetism, IUGG, Committee for Advice to Developing Countries in the Field of Geogesy and Geophysics, published under the auspices of UNESCO.
5 Akasofu, S. -I. and Kiseabeth, J. (1980): The Sq magnetic variation, equivalent current and field-aligned current distribution obtained from the IMB Alaska Meridian Chain of magnetometers, , 85, AS, 2085—2091.
6 Kamide, Y. and Brekke, A. (1985): Auroral electro jet current density deduced from the Chatanika radar and from the Alaska meridian chain of magnetic observatories, ., 80, 587.
J. Geophys. Res